In a recent user interface, an expression referred to as a Cover Flow display (Cover Flow is a registered trademark of Apple Inc., the mention of which will be omitted from now on) is used frequently.
Cover Flow has a function of arranging a plurality of images (such as album jacket pictures as to music players, and printed images of first pages as to document files) in a page and displaying them. It can move the images displayed on a page under the operation of a user to switch the images to be displayed, thereby being able to display images that cannot be displayed on a single page.
If a device that displays Cover Flow is a terminal with a touch screen, a user can move a plurality of images by a finger swipe operation referred to as a flick when the user wishes to switch the images to be displayed, for example.
FIG. 13 is a diagram illustrating an example of displaying five images by scrolling in a horizontal direction, in which each square designates an image.
When such a plurality of images constitute an animation, the individual images seems alike. Accordingly, when moving the plurality of images in the right direction, for example, a phenomenon of producing an illusion can sometimes occur that the plurality of images are moving in the left direction.
The phenomenon is called a wagon wheel phenomenon, and a method of preventing the wagon wheel phenomenon is disclosed in the following Patent Documents 1-3.
A Patent Document 1 discloses, to prevent the wagon wheel phenomenon as to the rotation of tires when shooting a vehicle, a method of setting controlled variables (the rotation speed of the tires and the frequency of a camera) so that the tires appear to be rotating in the forward direction according to information about the number of patterns of the tires, the frequency of the camera and a moving state of the vehicle.
This enables a viewer of the animation to perceive that the tires are rotating in the forward direction.
A Patent Document 2 discloses a technique suitable to be applied to a game machine such as a pachinko machine.
More specifically, when displaying patterns imitating reels used for a slot machine on a liquid crystal panel as an object, although the patters are variably displayed to be seen as if real reels were rotating, a problem can sometimes occur in that the patterns appear or disappear while the moving speed of the patterns variably displayed is changed successively. In addition, since the positions that enable reading the patterns move everywhere of a band variably displayed, a problem can sometimes occur of providing visually unpleasant images.
To prevent the foregoing problems, the Patent Document 2 displays the patterns at variable speed that makes them appear to move at a prescribed speed or less or to be stopped according to the relationships between a frame feed speed of the images and the intervals of the patterns. In addition, as for a proper slot machine, although the individual patterns differ, the patterns of the same type are displayed for a fixed interval.
Thus, specific patterns become readable at specific positions, thereby being able to prevent the patterns from becoming readable or unreadable. In addition, it can prevent unpleasant display such as flickering involved in the switching of the patterns.
A Patent Document 3 discloses, in an animation playback engine that displays an animation in a double buffer method, a method of continuously displaying the animation by displaying images in which the previous buffer and the next buffer are superimposed to prevent intermittent movement of the animation due to a stroboscopic effect.